This is a Microsoft SQL Server forum, so there would be few people, if any, who can advise you on Oracle.
In SQL Server, formatting and presenting the data is deferred to the presentation layer entities such as SQL Reporting Services, or other front-end code/applications. The SQL Server engine has no features that allows displaying the query results in a different color etc.
In MS SQL, you could use @@ROWCOUNT to see how many rows were returned by the last query. Then, if it's 0, you can display a message saying so. For instance:
select *
from employees
where
if @@ROWCOUNT = 0
select 'No rows selected.'
I just googled it, and it looks like SQL%ROWCOUNT is the Oracle version of that variable, but I'm no Oracle expert.